U.S. patent number 9,192,487 [Application Number 14/202,771] was granted by the patent office on 2015-11-24 for joint control systems and methods utilizing muscle activation sensing.
This patent grant is currently assigned to Arizona Board of Regents on behalf of Arizona State University. The grantee listed for this patent is Arizona Board of Regents, a body corporate of the State of Arizona, acting for and on behalf of Arizona State University. Invention is credited to Thierry Flaven, Thomas G. Sugar, George Wolf.
United States Patent |
9,192,487 |
Flaven , et al. |
November 24, 2015 |
Joint control systems and methods utilizing muscle activation
sensing
Abstract
A system and method for controlling a prosthetic limb are
provided. A sensor component receives input from a wearer's muscle
and provides a signal to a control component. The sensor component
may be a force sensing resistor placed inside a socket of a
prosthetic limb between a residual limb and the hard side of the
socket. The control component processes the signal and provides
instructions to an actuation component. In this manner, an
actuation component may move a joint, or may change the velocity of
a joint, or may change other characteristics of the prosthetic
limb.
Inventors: |
Flaven; Thierry (Saint Pierre
d'Allevard, FR), Sugar; Thomas G. (Tempe, AZ),
Wolf; George (Mesa, AZ) |
Applicant: |
Name |
City |
State |
Country |
Type |
Arizona Board of Regents, a body corporate of the State of Arizona,
acting for and on behalf of Arizona State University |
Scottsdale |
AZ |
US |
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Assignee: |
Arizona Board of Regents on behalf
of Arizona State University (Scottsdale, AZ)
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Family
ID: |
51488812 |
Appl.
No.: |
14/202,771 |
Filed: |
March 10, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20140257521 A1 |
Sep 11, 2014 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61775888 |
Mar 11, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F
5/01 (20130101); A61B 5/7214 (20130101); A61F
2/72 (20130101); A61B 5/7203 (20130101); A61B
5/7207 (20130101); A61F 2/76 (20130101); A61F
2/70 (20130101); A61F 2/74 (20210801); A61F
2002/7635 (20130101); A61F 2002/7615 (20130101); A61F
2/6607 (20130101); A61B 5/6811 (20130101) |
Current International
Class: |
A61F
2/72 (20060101); A61F 5/01 (20060101); A61F
2/66 (20060101); A61F 2/68 (20060101); A61F
2/76 (20060101); A61B 5/00 (20060101); A61B
5/01 (20060101); A61F 2/74 (20060101) |
Field of
Search: |
;623/24,25 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
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|
Primary Examiner: Sweet; Thomas J
Assistant Examiner: Bahena; Christie
Attorney, Agent or Firm: Snell & Wilmer L.L.P.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to, and the benefit of, U.S.
Provisional Application Ser. No. 61/775,888 entitled "JOINT CONTROL
SYSTEMS AND METHODS UTILIZING MUSCLE ACTIVATION SENSING" and filed
Mar. 11, 2013, the contents of which are incorporated herein by
reference.
Claims
What is claimed is:
1. A prosthetic device control system, comprising: a prosthetic
device comprising: a prosthetic ankle joint; a first sensor set
comprising: a first sensor set comprising four sensor components
arranged in a Wheatstone bridge; wherein, when the prosthetic
device is coupled to a residual limb, two of the sensor components
are located on top of one another and coincident with an axis of
force of a muscle of the residual limb and two of the sensor
components are adapted to be located coincident with an axis of
force of at least one of sheer stress or normal stress between a
socket of a prosthesis the prosthetic device and the residual limb,
whereby common mode sensed force is filtered, and wherein each
sensor component comprises a force sensing resistor disposed within
the socket of a prosthesis the prosthetic device, and wherein the
sensor component is adapted to be compressed against the socket by
the muscle of the residual limb; a control component coupled to the
first sensor set; and an actuation component coupled to the control
component, wherein the first sensor set receives an input from the
wearer of the prosthetic device and transmits a signal to the
control component, wherein the control component processes the
signal received from the first sensor set, wherein the actuation
component is coupled to the control component and modifies a first
characteristic of the prosthetic ankle joint in response to a first
instruction received from the control component, and wherein the
first characteristic is selected from the group consisting of:
position, velocity, force, or stiffness.
2. The system according to claim 1, wherein, when the prosthetic
device is coupled to the residual limb, each sensor component is
adapted to be located against the medial gastrocnemius muscle.
3. The system according to claim 1, wherein the control component
comprises: a force sensor interface component; and a first logical
controller, whereby the force sensor interface component
electrically interfaces a sensor component and the first logical
controller.
4. The system according to claim 3, wherein the force sensor
interface component comprises a voltage divider.
5. The system according to claim 3, wherein the first logical
controller comprises a dynamic pace controller configured to
provide control impulses to the actuation component corresponding
to a power profile of the actuation component having a non-linear
power trend in response to a dynamic load on the actuation
component.
6. The system according to claim 3, wherein the first logical
controller is configured as a tibia-based controller comprising a
tibia angle sensor and configured to sense a tibia angular velocity
and a tibia angle and provide corresponding control impulses to the
actuation component.
7. The system according to claim 3, wherein the first logical
controller comprises pre-loaded models corresponding to
characteristics comprising stride length and speed of a wearer
under a plurality of conditions.
8. The system according to claim 3, wherein the first logical
controller is configured with digital filtering logic.
9. The system according to claim 1, wherein the actuation component
is selected from the group consisting of: a robotic tendon, an
electric motor, a hydraulic actuator, a pneumatic actuator, or a
rheological fluid actuator.
10. The system according to claim 1, further comprising a second
sensor set comprising four sensors arranged at points
anterior-proximal and posterior distal in the sagittal plane
relative to the four sensors of the first sensor set.
Description
TECHNICAL FIELD
The present disclosure relates to prosthetics, and in particular to
sensing muscle activation in a residual limb to control a
prosthetic device.
BACKGROUND
Controllable prosthetic devices for replacement of amputated or
damaged limbs, such as hands, arms, legs, feet, and/or the like,
have long been desirable, for example in order to improve quality
of life for amputees. However, based at least in part on the amount
of body tissue that is no longer present, control of such devices
has often been rudimentary and/or poorly aligned to natural human
movement.
For example, prior approaches for prosthetic ankle control have
placed pressure sensors and force sensing resistors on the
prosthetic foot to measure ground reaction forces. However, because
of the number of steps and repeated kinetic shock, the force
sensing resistors are not able to withstand the forces at the foot;
they tend to break or the signal drifts over time.
Additionally, prior approaches have included using electromyography
(EMG) and fine wire EMG sensors inside a prosthetic socket to
determine muscle activation. However, the socket is often wet from
perspiration, and the residual limb typically "pistons" up and down
in the socket, so EMG sensor placement has been difficult and the
resulting EMG readings are highly variable, making them poorly
suited for use in prosthetic control. Accordingly, improved systems
and methods for prosthetic control remain desirable.
SUMMARY
In various embodiments, a prosthetic control system is disclosed. A
prosthetic control system may have a sensor component, a control
component, and an actuation component. The sensor component may
receive an input from the wearer of a prosthetic device and
transmit a signal to a control component. The control component may
process the signal received from the sensor component, and the
actuation component may be coupled to the control component. The
actuation component may modify a first characteristic of a
prosthetic device in response to a first instruction received from
the control component.
In various embodiments, a method of controlling a prosthetic device
is disclosed. In various embodiments, the method may include
receiving, by a sensor component, an input from the wearer of a
prosthetic device. The sensor component may transmit a signal to a
control component in response to the input. The control component
may process the signal and determine a first instruction in
response to the processing. Furthermore, the control component may
transmit the first instruction to an actuation component. The
actuation component may modify a first characteristic of a
prosthetic device in response to the first instruction.
BRIEF DESCRIPTION OF THE DRAWINGS
With reference to the following description, appended claims, and
accompanying drawings as attached:
FIG. 1 illustrates an exemplary prosthetic control system in
accordance with various embodiments;
FIG. 2A illustrates exemplary sensor placement in an exemplary
prosthetic control system in accordance with various
embodiments;
FIG. 2B illustrates use of an exemplary prosthetic control system
in connection with control of a prosthetic ankle in accordance with
various embodiments;
FIG. 2C illustrates use of an exemplary prosthetic control system
in connection with control of a brace in accordance with various
embodiments;
FIG. 3 illustrates various elements of an exemplary prosthetic
control system, in accordance with various embodiments;
FIG. 4 illustrates various aspects of a prosthetic control system
having four force sensing resistors in a Wheatstone bridge
configuration in accordance with various embodiments;
FIG. 5 illustrates exemplary sensor placement in an exemplary
prosthetic control system having four force sensing resistors with
two force sensing resistors placed on top of each other on the
muscle belly and two force sensing resistors placed adjacent to the
muscle belly, in accordance with various embodiments;
FIG. 6 illustrates exemplary sensor placement in an exemplary
prosthetic control system for a below the knee prosthetic having a
plurality of sensor components in accordance with various
embodiments;
FIG. 7 illustrates various aspects of an exemplary sensor component
having a force sensing resistor between a pad and a mounting plate;
and
FIG. 8 illustrates exemplary sensor placement in an exemplary
prosthetic control system having a control sleeve having four force
sensing resistors in accordance with various embodiments;
DETAILED DESCRIPTION
The following description is of various exemplary embodiments only,
and is not intended to limit the scope, applicability or
configuration of the present disclosure in any way. Rather, the
following description is intended to provide a convenient
illustration for implementing various embodiments including the
best mode. As will become apparent, various changes may be made in
the function and arrangement of the elements described in these
embodiments without departing from the scope of principles of the
present disclosure.
For the sake of brevity, conventional techniques for pressure
sensing, electronic control, biomechanical activation, and/or
well-known physical and mathematical relationships may not be
described in detail herein. Furthermore, the connecting lines shown
in various figures contained herein are intended to represent
exemplary functional relationships and/or physical or communicative
couplings between various elements. It should be noted that many
alternative or additional functional relationships or physical or
communicative connections may be present in a practical prosthetic
control system.
Prior approaches to prosthetic control have suffered from various
deficiencies, for example poor calibration, inaccurate response,
limited functional lifetime, and so forth. In contrast, exemplary
prosthetic control systems configured in accordance with principles
of the present disclosure provide reliable and accurate control of
prosthetic devices, for example prosthetic ankle joints.
In accordance with principles of the present disclosure, a
prosthetic control system may be any system configured to control a
prosthetic device based at least in part on input from the wearer
of the prosthetic device. In accordance with an exemplary
embodiment, and with reference to FIG. 1, a prosthetic control
system 100 generally comprises a sensor component 110, a control
component 120, and an actuation component 130. Sensor component 110
is configured to receive an input from the wearer of a prosthetic
device. Control component 120 is coupled to sensor component 110,
and is configured to process signals received from sensor component
110. Actuation component 130 is coupled to control component 120,
and is configured to activate, move, reposition, adjust, and/or
otherwise modify a first characteristic of a prosthetic device, for
example responsive to signals from control component 120. Moreover,
a prosthetic control system 100 may be configured with any
appropriate components and/or elements configured to provide
control of a prosthetic device.
For example, in various embodiments, a prosthetic may comprise a
first prosthetic member, a second prosthetic member, and a
prosthetic control system arranged to control a first
characteristic of the prosthetic. In various embodiments, this
first characteristic comprises the movement of the second
prosthetic member relative to the first prosthetic member. For
example, with reference to FIGS. 2B and 2C, a prosthetic control
system 100 may be positioned so that sensor component 110 and an
actuation component 130 are disposed between first prosthetic
member 302 and second prosthetic member 304. In this manner,
prosthetic control system 100 controls the movement of second
prosthetic member 304 relative to first prosthetic member 302. In
various embodiments, first prosthetic member 302 comprises a socket
into which a residual limb may be inserted, and second prosthetic
member 304 comprises a jointed component, for example, an
artificial foot, mechanically connected to the socket by an
articulating joint and/or brace.
With reference again to FIG. 1, in various embodiments, sensor
component 110 may comprise any suitable pressure sensor, for
example a force-sensing resistor (FSR). Moreover, sensor component
110 may comprise a strain gauge, a piezoelectric and/or
piezoresistive sensor, a capacitive sensor, an optical sensor,
and/or the like. In various embodiments, more than one sensor
component 110 is incorporated. By implementing more than one sensor
component 110, pressure from a variety of locations may be sensed,
for example, to permit more degrees of control, to permit more
precise control, and/or to aid in filtering out noise, for example
common-mode noise.
In various exemplary embodiments, sensor component 110 is affixed
to and/or coupled to a portion of a prosthetic. For example, with
reference to FIGS. 2B and 2C, in various embodiments, a sensor
component 110 is disposed inside a first prosthetic member 302. In
various exemplary embodiments, a sensor component 110 is affixed to
the socket of a prosthetic. In other exemplary embodiments, a
sensor component 110 is installed in the socket liner. Moreover, a
sensor component 110 may be disposed at any suitable location, for
example a location configured to sense muscle activation of a
residual limb. When a muscle of the residual limb is flexed, it
pushes against sensor component 110, which is in turn pressed
against the socket, and thus compressed. In this manner, the sensor
component 110 may detect a force or pressure exerted by the muscle
and/or otherwise detect activation of the muscle.
With additional reference to FIG. 2A, in an exemplary embodiment, a
sensor component 110 may be affixed to the first prosthetic member
302. In various embodiments, the first prosthetic member 302
comprises a hard socket adapted to receive a residual limb
comprising a muscle 400. When the muscle 400 is flexed, the muscle
400 pushes against the sensor component 110. The amount of pressure
detected by a sensor component 110 may be utilized by control
component 120 (see FIG. 1), for example to determine a position,
velocity, or force for a component of a prosthetic, for example an
ankle joint 132 (see FIG. 2B) and/or a brace 134 (see FIG. 2C)
and/or a second prosthetic member 304 (see FIG. 6).
For example, with reference now to FIG. 2A wherein a detailed view
of an exemplary sensor placement is illustrated, in various
embodiments a sensor component 110 is located in a position wherein
the pressure exerted by a muscle 400 on the sensor component 110 is
adequately reacted by the first prosthetic member 302 so that
sensor component 110 does not move and/or is not dislocated
relative to first prosthetic member 302 when pressed. Additionally,
the sensor component 110 may be located in a position wherein the
axis of force exerted by the muscle 400 is approximately tangential
and/or perpendicular to the shear/stress forces created when the
socket contacts the residual limb while in use. For example, with
reference to FIGS. 2B and 2C, the sensor may be located on the
first prosthetic member 302 in a position substantially coplanar to
a plane lying normal to the axis of ankle joint 132. Alternatively,
the sensor component 110 may be located in any position arranged to
diminish unwanted signal noise, for example noise caused by the
residual limb contacting the socket.
Moreover, in various example embodiments, multiple sensor
components 110 having four force sensing resistors may be
implemented, for example, to capture and detect pressure variations
as a determination of gait events. For example, it is expected that
during level ground walking sensor pairs located at points
anterior-proximal and posterior-distal in the sagittal plane would
rise and fall together.
For example, with reference to FIG. 6, in various embodiments, four
sensor components 110 may be implemented as a first sensor set 640
and four sensor components 110 may be implemented as a second
sensor set 650. First sensor set 640 and second sensor set 650 may
be positioned so that corresponding sensor pairs located at points
anterior-proximal and posterior-distal in the sagittal plane rise
and fall together.
With reference to FIG. 8, a sensor component 110 may be positioned
in a control sleeve 800. While a sensor component may be mounted
inside a portion of a prosthetic, as discussed elsewhere herein, in
various embodiments, a sensor component may be mounted inside a
separate control sleeve 800. In various embodiments a control
sleeve 800 comprises a fabric sleeve 801, sensor component 110, and
retention element 803. In various embodiments, fabric sleeve 801
wraps sensor component 110 and maintains sensor component 110 in
contact with a portion of a body, for example forearm 802.
Retention element 803 may comprise an elastic band or the like.
Retention element 803 may be tightened around the sleeve, for
example, so that a firm but comfortable bias force maintains sensor
component 110 position. In this manner, the opening and closing of
a wearer's hand may be detected by the sensing of muscle activation
in the forearm 802. In accordance with the principles herein,
sensor component 110 may be mounted in a control sleeve 800. For
example, four sensor components 110 comprising force sensing
resistors may be implemented in communication with a sensor
component interface component 501 comprising a Wheatstone
bridge.
In accordance with principles of the present disclosure, in various
embodiments, the sensor component 110 is located in the popliteal
depression, for example behind the knee. In various embodiments,
the sensor component 110 is located at the medial gastrocnemius.
Moreover, the sensor component 110 may be located at the lateral
gastrocnemius, for example as illustrated in FIGS. 2B and 2C. The
sensor component 110 may be located at any location selected to
permit a desired muscle to exert a desired pressure and having
sufficiently minimal noise to permit reliable operation. With
reference to FIG. 2A, in various embodiments, the force exerted on
the sensor component 110 may be varied by the wearer in response to
the wearer variably contracting the muscle 400.
With renewed reference to FIG. 1, in various exemplary embodiments
control component 120 may comprise any suitable electronic
components configured to provide control of a prosthetic device (or
portion thereof) in response to a signal from sensor component 110,
for example microprocessors, electronic memories, communications
ports and associated protocols, and/or the like. In an exemplary
embodiment, control component 120 comprises one or more of a force
sensor interface component and one or more of a logical
controller.
With reference now to FIGS. 1 and 3, in various embodiments control
component 120 comprises a force sensor interface component 501. In
various embodiments, a force sensor interface component 501 may
comprise a voltage divider circuit, a Wheatstone bridge circuit,
and/or the like. In various embodiments, a voltage divider circuit
may be implemented. A voltage source may be divided across two
resistors, and the divided voltage may be measured at the juncture
of the resistors. For example, a force sensing resistor may be
disposed between a voltage source and a first juncture. A fixed
resistor may be disposed between the first juncture and a voltage
sink. The divided voltage may be measured between the voltage sink
and the juncture. In this manner, as the resistance of the force
sensing resistor varies in response to the degree of pressure
exerted on the force sensing resistor by the wearer's muscle, the
divided voltage correspondingly varies, and such voltage may be
utilized in connection with operation and/or control of prosthetic
control system 100.
In other example embodiments, the force sensor interface component
501 may comprise a Wheatstone bridge. In this manner, common mode
noise may be filtered, for example, by implementing multiple force
sensing resistors in a Wheatstone bridge configuration. In various
other embodiments, only one force sensing resistor is implemented.
In certain embodiments, a Wheatstone bridge is implemented, for
example to facilitate different interconnections between various
aspects of a logical controller and a force sensor interface
component.
For example, with reference to FIG. 4, in conjunction with at least
one sensor component 110, a force sensor interface component 501
comprises a Wheatstone bridge circuit connecting four sensor
components 110. A Wheatstone bridge may be used in sensor
electronics to amplify small signals while rejecting common,
extraneous signals such as temperature and or drift. In various
embodiments, four resistors are arranged in two branches of two
resistors connecting at the positive and negative voltage source.
Four sensor components 110 may be connected with a force sensor
interface component 501 comprising a Wheatstone bridge. For
example, resistor 502-1, resistor 502-2, resistor 502-3, and
resistor 502-4 may comprise force sensing resistors. In this
regard, a constant voltage, Va, is applied to the circuit across
positive input terminal 511 and negative input terminal 512. A
sensed voltage, Vs, is measured across the bridge circuit output
terminal 513 and negative output terminal 514.
In various example embodiments, four sensor components 110
comprising force sensing resistors are arranged in a single
Wheatstone bridge shown in FIGS. 4, 5, 6, and 8. The sensors are
arranged so that resistor 502-2 and resistor 502-3 are on top of
each other and, ideally, measure substantially the same force. The
force from the socket pressure plus the muscle activation force are
measured by resistor 502-2 and resistor 502-3 while resistor 502-1
and resistor 502-4 measure the same residual level of pressure or
force inside the socket. As shown in FIGS. 5, 6, and 8, resistor
502-2 and resistor 502-3 are placed on the muscle belly while
resistor 502-1 and resistor 502-4 are placed to the side of the
muscle belly. When the pressure or force measured by resistor 502-1
equals resistor 502-4, and the pressure or force measured by
resistor 502-2 equals resistor 502-3, the circuit gain equation
simplifies to:
.times..times..times..times..times..times..times..times.
##EQU00001## where R.sub.FSR1 is resistor 502-1, R.sub.FSR2 is
resistor 502-2, R.sub.FSR3 is resistor 502-3, and R.sub.FSR4 is
resistor 502-4.
The voltage sensed is directly proportional to the difference in
resistance, R, of resistor 502-1 and resistor 502-3. The
denominator is the sum of the resistance, R, of resistor 502-1 and
resistor 502-3. The circuit measures the difference in pressure
between the activated muscle and the residual limb pressure. This
principle of arranging four sensors in a bridge circuit enhances
wearer control by allowing muscle activation pressures to be
detected while in a seated position or standing and walking.
Because the muscle activation force is large compared to normal
residual limb pressure, for example as exerted by a residual limb
on a surrounding socket, customizations and variations in the
sensor placement may be reduced. Additionally, the system may not
need to be recalibrated when the wearer dons and doffs the
device.
In various embodiments, a force sensor interface component 501 is
implemented in conjunction with at least one sensor component 110
wherein a Wheatstone bridge has three fixed resistors and one
sensor component 110, for example, comprising a force sensing
resistor or a pressure sensor. However, in various embodiments, as
previously disclosed herein, a force sensor interface component 501
is implemented in conjunction with at least four sensor components
110 wherein a Wheatstone bridge has four sensor components 110, for
example, each comprising a force sensing resistor or a pressure
sensor. One having experience in the art will appreciate that any
number of sensor components and or force sensor interface
components, having any number of force sensing resistors may be
implemented, to achieve various performance characteristics. For
example, one force sensing interface component 501 may be
implemented with four sensor components 110 comprising force
sensing resistors thus providing a benefit of less calibration and
fewer wires, and the system may measure the difference between the
pressure on the flexed muscle inside the socket compared to the
residual pressure inside the socket.
In various example embodiments, a sensor component 110 comprises at
least one force sensing resistor, a mounting plate, and a convex
pad. For example, with reference to FIG. 7, in various embodiments
a sensor component 110 comprises a force sensing resistor 701
adhered to a mounting plate 603. In various embodiments the
mounting plate is acrylic, although it may be any material adapted
to provide support to the force sensing resistor 701. Furthermore,
the sensor component 110 may comprise a pad 601. In various
embodiments, the pad is convex, although the pad may be any shape
adapted to transmit pressure to the force sensing resistor 701.
Still furthermore, in various embodiments, the pad comprises
acrylic, although the pad may be any material adapted to provide
support to the force sensing resistor 701.
In various embodiments, control component 120 comprises a first
logical controller 503. Moreover, a control component 120 may
comprise a logical controller comprising a dynamic pace controller.
In various embodiments, a dynamic pace controller may be calibrated
to provide control impulses to the actuation component 130, for
example pulses corresponding to the power profile of the actuation
component 130. For example, actuation component 130 may have a
non-linear power-in to power-out trend. For example, the input
current required to actuate the actuation component 130 may be
non-linear versus the load on the actuation component 130. In
various embodiments, the kinetic energy of a moving prosthesis may
influence the power profile of the actuation component 130. Thus,
in various embodiments, the control impulses may be adapted in
correspondence to the power profile of the actuation component
130.
In various embodiments wherein prosthetic control system 100 is
utilized in connection with an artificial foot and/or leg, control
component 120 may comprise a logical controller utilizing
tibia-based information. For example, the tibia angular velocity
and the tibia angle may be sensed and a corresponding control
signal may be transmitted to actuation component 130. Thus, in
various embodiments, the control component 120 or the sensor
component 110 may further comprise a tibia angle sensor, for
example, an angular rate sensor whereby the angular velocity and
the tibia angle may be evaluated.
In accordance with various embodiments, control component 120 may
comprise multiple logical controllers. For example, a control
component 120 may comprise a first logical controller 503 and a
second logical controller 505. In various embodiments, control
component 120 may comprise any number of logical controllers, for
example, a first logical controller 503, a second logical
controller 505, and an Nth logical controller 507. In various
embodiments, a different logical controller may be activated
depending on different signals received from the sensor component
110. In this manner, the wearer may change the operation of control
component 120. For example, a different logical controller may be
selected depending on different use profiles for prosthetic control
system 100 and/or an associated prosthetic device, for example,
sitting, standing, leaning, walking, running, bicycling, and
driving a vehicle, among others. Moreover, control component 120
may be responsive not only to variable force imparted on sensor
component 110, but control component 120 may also be responsive to
sequences and patterns of muscle contraction. For example, a wearer
may alternately flex and unflex a muscle to encode control messages
for decoding by control component 120. In this manner, the wearer
may reconfigure or change the operation of control component 120.
In various embodiments, a control component 120 may have a training
mode wherein the wearer can customize the behavior of the control
component 120 based at least in part on the wearer's gait and
preferences.
In various embodiments, control component 120 comprises a logical
controller comprising pre-loaded models. For example, in a tibia
based controller, a variable mathematical relation between a tibia
angle (e.g., the residual limb) and the ankle angle (e.g., an angle
associated with the ankle joint 132) (FIGS. 2B-C) may be modeled.
Moreover, a tibia global angular position may be modeled. Moreover,
a model may correspond to different points along a wearer's gait,
and different models may correspond to different stride lengths.
Thus, the control component 120 may select from among a plurality
of pre-loaded models corresponding to the natural gait of a wearer
under a plurality of conditions, for example wherein the selecting
chooses a pre-loaded model corresponding to a desired gait and
conditions. In various embodiments, the conditions may be derived
by the controller from the input signals, or the conditions may be
manually selected by the wearer, in accordance with the principles
disclosed herein. In this manner, the system may approximate the
natural gait of a wearer under a variety of conditions, for example
so that the wearer can run or walk at various speeds and with
various stride lengths.
In various embodiments, a control component 120 comprises a logical
controller configured with digital filtering logic. For example,
digital filtering logic may be implemented as at least one of
polynomial functions, moving integral algorithms, calibration
curves, and/or the like. The functions, algorithms, and/or curves
may be revised over time, for example, as the prosthesis ages, or
as various components change, for example, as resistors drift, or
as a wearer's muscles grow or shrink. Moreover, filtering may be
adjusted as the seating of a residual limb in a socket may shift
during prolonged use. In this manner, control component 120 may
maintain accurate control over a prosthesis, even as external
and/or internal control factors vary and/or evolve.
Actuation component 130 is configured to receive signals from
control component 120. Actuation component 130 may change a first
characteristic of a prosthesis. In various exemplary embodiments,
actuation component 130 may comprise one or more of electric
motors, hydraulic actuators, pneumatic actuators, rheological
fluids, variable impedance actuators, powered springs, and/or the
like. Moreover, an actuation component 130 may comprise any
suitable rotary and/or linear actuator, as desired. In various
exemplary embodiments, an actuation component 130 may comprise a
variable damping element, for example a hydraulic valve, a
rheological fluid, and/or the like. An actuation component 130 may
be configured to adjust one or more characteristics of a
prosthetic, for example a joint position, a brace position, a joint
resistance to further angular movement, and/or the like.
For example, in various embodiments, actuation component 130
comprises a robotic tendon. In various embodiments, a robotic
tendon comprises a motor, a screw, and a pair of metal springs. The
motor is in mechanical communication with the screw, and turns the
screw when activated. In various embodiments, the screw is adapted
to stretch the springs. For example, in various embodiments, the
actuation component 130 may activate the motor in response to a
signal from control component 120. In this manner, the motor turns
the screw. The springs are stretched in response to the turning.
The actuation component 130 may also reverse the direction of the
motor in response to a signal from control component 120. In this
manner, the springs are unstretched and/or compressed in response
to the turning. By alternately stretching and
unstretching/compressing the springs at different points in a
wearer's stride, energy may be stored and released during a
wearer's gait cycle, enabling mimicking of able-bodied walking
behavior.
Additionally, the springs may lower the peak power requirement and
energy consumed during the gait cycle, for example because energy
is stored in the springs by the compression and expansion naturally
occurring when supporting the wearer's body weight, in addition to
being stored in the springs by the motor. As a result, a more
efficient prosthesis may be realized.
With reference now to FIG. 1 and FIGS. 2B-2C, in an exemplary
embodiment, prosthetic control system 100 is configured to adjust
the position and/or angular velocity of an ankle joint 132 for a
prosthetic ankle, orthosis, or brace 134. In various embodiments,
with reference to FIGS. 1 and 6, a prosthetic control system 100
may be configured to adjust the position of a second prosthetic
member 304 relative to a first prosthetic member 302. In various
embodiments, with reference to FIGS. 1, 2B-2C, and 6, muscle
activation information detected by sensor component 110 is
delivered to control component 120, and control component 120
generates commands to actuation component 130. Responsive to the
commands, actuation component 130 moves the ankle joint 132 and/or
brace 134 and/or second prosthetic member 304. In this manner,
position of a prosthetic foot may be controlled by volitional input
(for example, calf muscle activation) from the wearer.
Moreover, in various embodiments, a prosthetic control system 100
may be configured to permit a wearer to position a prosthesis as
desired, for example to rest a foot flat on the floor when sitting.
For example, with reference to FIG. 1 and FIGS. 2A-2C, a wearer may
contract a muscle 400 in proximity to a sensor component 110.
Muscle 400 may exert a force on the sensor component 110, and
trigger the control component 120 to direct the actuation component
130 to articulate a second prosthetic member 304 about an ankle
joint 132 relative to a first prosthetic member 302. In various
embodiments, the first prosthetic member 302 comprises a partial
shin prosthetic and second prosthetic member 304 comprises a foot
prosthetic. In this manner, the foot prosthetic may be articulated
about ankle joint 132 to enable the foot to rest flat on the floor
or otherwise assume a desired position and/or orientation.
It will be appreciated that, as the pressure signal from sensor
component 110 is varied, the position of the ankle joint 132 may be
moved. Moreover, as the pressure signal from sensor component 110
is varied, the angular velocity of the ankle joint 132 may be
modified. Yet further, as the pressure signal from sensor component
110 is varied, the stiffness of the ankle joint 132 may be varied,
for example via rheological fluids, springs, or variable impedance
actuators. Additionally, as the pressure signal from sensor
component 110 is varied, the force applied by actuation component
130 at the ankle joint 132 may be varied. Stated generally, the
varying pressure signal from sensor component 110 may be utilized
to vary, modify, and/or control any suitable attribute or
characteristic of a prosthetic device. In this manner, improved
wearer volitional control of the prosthetic device is
facilitated.
Via utilization of prosthetic control system 100, a wearer can
achieve control of a prosthesis, for example control of plantar
flexion (downward movement) of a prosthetic foot via a powered
bionic ankle. Thus, the wearer can obtain additional push-off power
when walking, ascending stairs or slopes, and so forth.
Additionally, the wearer can move the foot downward to push on a
pedal, for example in order to control a motor vehicle.
It will be appreciated that while principles of the present
disclosure may be discussed in connection with exemplary
embodiments related to control of a prosthetic device, such
principles may suitably be applied to braces, orthoses,
exoskeletons, and/or the like. Additionally, principles of the
present disclosure may be discussed in connection with exemplary
embodiments related to control of the ankle joint; however, such
principles may suitably be applied to the wrist, elbow, knee, hand,
and so forth. All examples and embodiments provided herein are by
way of illustration and not of limitation.
While the principles of this disclosure have been shown in various
embodiments, many modifications of structure, arrangements,
proportions, the elements, materials and components, used in
practice, which are particularly adapted for a specific environment
and operating requirements may be used without departing from the
principles and scope of this disclosure. These and other changes or
modifications are intended to be included within the scope of the
present disclosure and may be expressed in the following
claims.
The present disclosure has been described with reference to various
embodiments. However, one of ordinary skill in the art appreciates
that various modifications and changes can be made without
departing from the scope of the present disclosure. Accordingly,
the specification is to be regarded in an illustrative rather than
a restrictive sense, and all such modifications are intended to be
included within the scope of the present disclosure. Likewise,
benefits, other advantages, and solutions to problems have been
described above with regard to various embodiments. However,
benefits, advantages, solutions to problems, and any element(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature or element of any or all the
claims.
As used herein, the terms "comprises," "comprising," or any other
variation thereof, are intended to cover a non-exclusive inclusion,
such that a process, method, article, or apparatus that comprises a
list of elements does not include only those elements but may
include other elements not expressly listed or inherent to such
process, method, article, or apparatus. Also, as used herein, the
terms "coupled", "coupling" or any other variation thereof, are
intended to cover a physical connection, an electrical connection,
a magnetic connection, an optical connection, a communicative
connection, a functional connection, and/or any other connection.
When language similar to "at least one of A, B, or C" or "at least
one of A, B, and C" is used in the claims, the phrase is intended
to mean any of the following: (1) at least one of A; (2) at least
one of B; (3) at least one of C; (4) at least one of A and at least
one of B; (5) at least one of B and at least one of C; (6) at least
one of A and at least one of C; or (7) at least one of A, at least
one of B, and at least one of C.
* * * * *